Processing control device for printing machines

ABSTRACT

A sheet registration control device utilized in a processing control system for a printing machine of the type having a plurality of processing steps and which utilizes a plurality of control pulses. A rotary switch actuator in operative conjunction with an adjustably fixed switch is arranged to initiate each working series of control signals for each sheet of paper introduced into machine processing.

United States Patent 1191 Koch et al,

[ Apr. 16, 1974 PROCESSING CONTROL DEVICE FOR PRINTING MACHINES [75]Inventors: Gilbert E. Koch, Rochester;

Lawrence C. Hubler, Fairport, both of NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Aug. 30, 1972 21 Appl. No.: 284,834

[52] US. Cl. 355/3, 271/53, 271/60, 355/14, 355/16 [51] Int. Cl..; G03g15/00 [58] Field of Search 355/3, l4, l7, 16;271/53,

[56] 1 References Cited UNITED STATES PATENTS 9/1972 Quant 118/72,787,951 4/1957 Shipley et a]. 271/60 x 1,991,003 2/1935 Stevens 27l/603,659,109 4/1972 Hickey et a1 ass/14 x PrimaryExaminer-Robert P. Greiner5 7] ABSTRACT A sheet registration control device utilized in aprocessing control system for a printing machine of the type having aplurality of processing steps and which utilizes a plurality of controlpulses. 'A rotary switch actuator in operative conjunction with anadjustably fixed switch is arranged to initiate each working series ofcontrol signals for each sheet of paper introduced into machineprocessing.

, 5 Claims, 10 Drawing Figures PATETEMPR 16 m4 7 3.804507 SHEEY E OF 5PAVENTEBAPR 16 1914 3.804; 507' MU 5 OF 5 This invention relates toprinting machines, and in particular toelectrostatic printing of thetype utilizing an endless photoreceptor element, such as a drum or belt,and a series of control signals for controlling machine processing.

Electrostatic printing machines of the type utilizing as endless beltforms of photoreceptor employ various processing stations which willuniformly charge, expose, develop, transfer, fuse, clean, etc. duringany cycle of copying. For high speed operation of these machines,especially for the endless belt type machine, it becomes very importantthat there be a proper base or starting point for the timing sequence ofoperation of the processing stations in order to maintain properregistration of all the processing functions relative to images. Theremust be provision for precise sheet regis; tration, the efficient andassured movement of sheets of copy paper to the transfer station of themachine in timed sequence relative to the production of electrostaticlatent images, the development thereof, the proper orientation of eachsheet to the developed image received at'the transfer station and thecommencin'g and duration for all the other processing requirements inthe machine including all the sensing elements utilized for sheetpresence monitoring for paper jam detection.

Therefore, the principal object of the present invention is to improveelectrostatic printing machines of the type employing electrostaticphotoreceptor elements in the form of a drum or belt and series ofcontrol pulses for the processing of each copy of an original.

Another object of the present invention is to maintain proper timing ofthe operation of the electrostatic processing stationsutilizecl in themachine so as to effect maximum efficiency in the operation of themachine especially for high speed reproduction.

The foregoing objects are attained by the timed sequence of operation ofcertain processing stations, based upon the movement of a photoreceptorelement which is sensed by a movement responsive device in the form ofthe directconnection between the element and its drive means. Machineprocessing is accomplished by utilizing a timing device directlyoperable with the drive means, the timingdevice generating a continuousseries of electricalpulses, some of which are used to initiate operationof the processing components in the machine. Periodic resetting of thetrain of pulses to zero is also effected, this being effectivelyaccomplished by a switching device once for each sheet of paper and onespacing between it and the next sheet,

or the time between the exposure flashes of the ma- These and otherobjects will become apparent after reading the following specificationin conjunction with the drawings wherein:

FIG. ii is a schematic sectional view of an electrostatic reproductionmachine embodying the principles of the invention;

FIG. 2 is a front elevational view of the drive motor for the machine;

FIG. 3 is a schematic view of the paper supply transports in relation toa sheet registration arrangement;

FIG. 4 is a partial plan view of one of the transports and theregistration arrangement;

FIGS. 5 and 6 are front and side elevational views respectively of aswitching mechanism utilized in sheet registration reset;

FIGS. 7, 8 and 9 are schematic views of the relative positioning ofregistration fingers during various sequences of operation; and

FIG. llll is an isometric view, partly broken away, of a variable speedimparting device.

For a general understanding of an electrostatic processing system inwhich the invention may be incorporated, reference is had to the"drawings wherein various components of a system are schematicallyillustrated. For purposes of illustration only, the type of printingmachine described for the environment of the present invention is of theelectrostatic type; and particularly one that is based on the process ofxerography. In most electrostatic systems, such as a xerographic machineof the type illustrated, a light image of an original to be reproducedis projected onto the sensitized surface of a xerographic plate to forman electrostatic latent image thereon. For purposes of providing anenvironment for the present invention and therefore, for illustrationpurposes only, the illustrated xerographic system is of the type whereinthe xerographic plate is in the form of an endless belt. in a belt typeenvironment, the present invention is also adapted for integration intoa belt type machine wherein the belt is a conveying element per serather than aform of photoreceptor, and sheets of photoconductivematerial are positioned upon the belt for movement through processingstations. Thereafter, the latent image is developed by means of amagnetic brush developing apparatus to form a xerographic powder image,corresponding to the latent image on the'plate surface. The power imageis then electrostatically transferred to a support surface to' which itmay be fixed by a fusing apparatus whereby the powder image is causedpermanently to adhere to the support surface.

The electrostatically attractable developing material commonly used inmagnetic brush developing apparatus comprises a pigmented resinouspowderreferred to here as ?toner and a carrier" of larger granular beadsformed with steel cores coated with a material removed in thetriboelectric series from the toner so that a triboelectric charge isgenerated between the toner powder and the granular carrier. Themagnetizable carrier also provides mechanical control for the formationof brush bristles by virtue of magnetic fields so that the toner can bereadily handled and broughtinto contact with the exposed xerographicsurface. The toner is then attracted to the electrostatic latent imagefrom the carrier bristles to produce a visible powder image on aninsulating surface.

In the illustrated machine, an original l) to be copied is placed upon atransparent support platen P fixedly arranged in an illuminationassembly generally indicated by the reference numeral 10. While upon theplaten, an illumination system comprising two or more lamps andreflectors L are flash energized so as to flash light rays upon theoriginal thereby producing image rays corresponding to the informationalareas on the original. The image rays are projected by means of anoptical system 11 to an exposure station A for exposing thephotosensitive surface of a moving xerographic plate in the form of aflexible photoconductive belt 12. In moving in the direction indicatedby the arrow, prior to reaching the exposure station A, that portion ofthe belt being exposed would have been uniformly charged by a coronadevice 13 located at a belt run extending between belt supportingrollers 14 and 15, the latter being the drive roller for the belt. Theexposure station extends between the roller 14 and a third supportroller 16, and the belt run between these rollers is encompassedentirely by the exposure station for minimizing the space needed for thebelt and its supporting rollers.

The exposure of the belt surface to the light image discharges thephotoconductive layer in the areas struck by light, whereby thereremains on the belt a latent electrostatic image in image configurationcorresponding to the light image projected from the original on thesupporting platen. As the belt surface continues its movement, theelectrostatic image passes around the roller 16 and through a developingstation B located at a third run of the belt and in which there ispositioned a developing apparatus generally indicated by the referencenumeral 17. Suitable means (not shown) such as vacuum panels orte'nsioning means may be utilized for maintaining the belt flat in anyor all three belt runs, and additionally the belt-run related to thedevel opment zone B is maintained at an inclined plane. The developingapparatus 17 comprises a plurality of magnetic brushes which carrydeveloping material to the adjacent surface of the upwardly movinginclined photoeonductive belt '12 in order to provide development of theelectrostatic image.

The developed electrostatic image is transported by the belt 12 to atransfer station C located at a point of tangency on the belt as itmoves around the drive roller whereat a sheet 'of copy paper is moved ata speed in synchronism with the moving belt in order to accomplishtransfer of a properly registered developed image.

Thereis provided at this station a transfer roller 19 which is arrangedon the frame of the machine for contacting the non-transfer side of eachsheet of copy paper as the same is brought into transfer engagement withthe belt 12. The roller 19is electrically biased with sufficient voltageso that a developed image on the belt 12 may be electrostaticallytransferred to the adjacent side of a sheet of paper as the same isbrought into contact therewith. I

There is also provided a copy sheet supplying apparatus comprising amain paper feed supply 20 and an auxiliary paper feed supply 21. Each ofthe paper supplies is adapted to separate sheets from their respectivesupply stacks seriatim and to.transport the sheets to a sheetregistration station and eventually into contact with the developedimage on the belt as the same is carried around the drive roller 15. Theprogramming or timing control arrangement of the present inventionisoperatively associated with each of the paper supply mechanisms 21,22-, the flash illumination devices L for producing an electrostaticlatent image on the belt 12, to present a developed image at thetransfer station C in timed sequence with the arrival of a sheet ofpaper, and is coordinated with the activation of other processing andcontrol devices at the precise time that these elements are to functionfor their intended purposes.

After the developed image is transferred to a sheet of paper, it isstripped from the belt 12, and conveyed by a conveying system 23 into afuser apparatus generally indicated by the reference numeral 24 whereinthe developed and transferred xerographic powder image on the sheetmaterial is permanently affixed thereto. After fusing, the finished copyis discharged from the apparatus by conveyor 25 at a suitable point forcollection externally of the apparatus. The remaining toner particlesremaining as residue on the developed images, and those particlesotherwise not transferred are carried by the belt 12 to a cleaningapparatus 26 positioned on the run of the belt between the rollers l4,15 adjacent the charging device 13. The cleaning device comprises acorotron 27 for neutralizing charges remaining on the particles and arotating brush 28 which operates in conjunction with a vacuum system toremove residual toner particles from the vicinity of the brush.

In order to impart continuous movement to the belt 12, there is provideda drive means 30 comprising a constant speed drive motor and gear boxwhich is directly coupled to the drive roller 15 by a suitable drivechain or timing belt 31 entrained around a sprocket or pulley mounted onthe shaft for the roller 15 and the output shaft 32 for the drive means.The present invention provides a specific arrangement to accomplishpulse generation off of the belt drive motor, and also an entirelydifferent arrangement for periodically resetting the pulse train to zerothereby establishing pitches. To this end, a gear 33 is mounted on thedrive shaft 32 for the drive means 30 and includes a predeterminednumber of teeth 34, each of which becomes aligned with a magnetic pickupelement 35 mounted on the frame of the machine during rotation of thegear. The element 35 is associated with a pulse generating device .36which produces a square wave signal having peaks corresponding to thesuccessive alignments of the teeth 34 with the pick up element 35.As-each tooth moves adjacent the device 35, the magnetic field in thedevice is set to vary and therebyproduce a peak in the signal.

Programming control for the machine processing steps is accomplished inconjunction with pitch reset wherein after a series of electrical pulsesare generated corresponding to the movement of each copy sheet plus onespacing through the transfer station, reset of this number, or pitch, isaccomplished when the photoreceptor belt has travelled a precise,predetermined distance 'as related to the movement of a copy sheet plusone spacing. Plus generation for a timing control signal then isaccomplished by utilizing a direct connection of the photoreceptor belt12 to the pulse generating device so as to move at all times directlytherewith as described above and reset is accomplished by a resetmechanism which is reset at a predetermined position of the leading edgeof each sheet of paper in proper registration to a developed image onthe photoreceptor belt. With the belt continuously moving and beingdriven by a drive directly connected to the processing programmingcontrol, each pitch reset occurs precisely at predetermined distances ofmovement of the belt.

The programming control then is acquired by means of a timing devicemechanically coupled to the shaft for the drive means 30 and which isdriven into operation when the roller is rotating. The pulse generatingdevice 36 which is part of the timing apparatus is set to produce acontinuous train of time pulses which can be determined by therotational speed of the drive means 30 and the number of teeth 34 on thegear 53. The device 36 is electrically connected to a counting device 37which may be in the form of a shift register mechanism which counts thepulses of the control signal. After a number of pulses have-beencounted, the count is restarted or set to zero which is described hereinas the pitch reset. Rather than having a predetermined number of pulsescause the reset, it is preferred to utilize the distance of movement ofthe belt 112 as the reset causing standard. This is accomplished, aswill be described hereinafter, by rotation of sheet registrationfingers. Any machine event or processing step can be initiated; thatis,turned On and Off" or to remain operative for any period of time on anyone or more of the discrete pulses. Pitch reset is accomplished duringsheet registration, after each revolution of registration fingers whichare arranged to be periodically inte rposed in the path of movement ofsheets of paper just immediately prior to the insertion of each sheetinto the nip of the transfer roller 19 and the belt 112 at station C. iI

Operatively associated with the sheet supply 20 is a sheet transportcomprising a plurality of continuously movablebelts 40 driven by themain 'drive by way of rollers'41. Similarly, the sheet supply 211 isassociated with a sheet transport comprising a plurality of belts 42movably driven around rollers 43, by the machine drive 30. Thedrivingforce for the transports 4t) and 42 may be accomplished by means otherthan the machine drive 30, such as by individual motors or a commonmotor. The transport 42 for the auxiliary paper supply means, when inthe operative. mode, transports each sheet fed thereto onto the beltsfor the main paper supply 20. In this arrangement, each of the papersupplies is provided with its own sheet transport and one of thetransports directs sheets carried thereby to the other transport so thata single sheet registration mechanism may. be employed for cooperationwith each of the sheet supplies.

As shown in FIGS. 3 and 4, sheet registration is accomplished by meansof a plurality of spaced registration fingers 45 mounted on a'shaft 46in alignment transversely of the paper sheet path. The shaft is suitablysupported for rotation on the machine frame and is operatively connectedby way of a variablespeed device 47 to a drive belt 48 which in turn isoperatively connected to the drive means 30 to be driven at a speedcoordinated withthe speed of the belt 12 and the two copy sheettransporting means 40, 32. For each complete rotation of the fingers 45in the direction of the arrow, and when they attain the position shownin FIG. 3, a sheet S is in engagement with the fingers to becomestraightened in its traveling and to become positioned and timed, inother words, registered. The distance between the fingers when a sheetis registered and the nip at stationC is arranged to be very small andprecisely known. The instant the fingers become disengaged from eachsheet, the sheets will be in the nip of a pair of driven registrationpinch rollers 50, 51 and these two 1 occurrences are utilized as thepitch reset event. The pulse occurring at that time by the countingmechanism 37 is given the designation as the zero pulse. All otherpulses are counted from that event, until the next registration for thenext sheet and the corresponding zero pulse. While the occurrence of theleading edge of the sheet S leaving the fingers 45 being synchronizedwith the entry of the edge into the nip of the pinch roller has beenchosen as the instant for pitch reset, it is to be understood that otheroccurrences may be utilized for this purpose. For instance, the pitchresetmay be made to occur when the fingers 34 are still in engagementwith the leading edge of a sheet and before it reaches the nip of thepinch rollers. What is important, however, is that this precise angularpositioning of the fingers for reset must be utilized for all resetoccurrences. Processing control and steps are set to be actuated orenergized at predetermined pulse counts from a zero pulse, and dependingupon the number of pulses to be generated, say on the order to 1,000pulses or so for each sheet registration, it will be appreciated thatvery close and accurate process control can be attained.

The lower registration pinch rollers 51 are mounted for rotation on ashaft 52 between the belts of the belt transport 40 and the fingers 45soas not to impede operation thereof. The shaft 52 is mounted forrotation in a frame (not shown) and is driven by belts 53 and pulleys 54associated with a drive shaft 55 also mounted on the machine frame. Oneof the shafts 55 is driven by way of a belt 56 from a clutch 57associated with the variable speed device 47. In this manner, the pinchrollers 51 are given their rotative drive by the belts 58 from themachine drive motor 30. The upper pinch rollers are idler rollers havingtheir peripheries in frictional engagement with the lower rollers 51 tobe rotated therewith.

In order to effect pitch reset at the precise angular positioning of theregistration fingers for each revolution thereof and to permit therecounting of pulses from each zero pulse at sheet registration, aswitching mechanism 55 having a'switch associated therewith to beactuated to a controlling position precisely as a sheet isregistered-and the fingers arein a predetermined angular position.

The switching mechanism 58 comprises a circular flat housing 59 havingtwo half sections 60 and 61, the former being suitably mounted on themachine frame and the latter secured by screws 62 to the section 60 soas to forms flat circular chamber 63 within the housing 59. In the axialcenter of the circular casing there is formed a central boss having anopening through which the end of the registration shaft 46 projects.Movable within the space on chamber 63 is a switch member 64 which issecured to the shaft 46 to be rotated therewith. The member 64 isarranged to be rotated within the chamber 65, and is provided with acircular magnet 65 that scribes a circular path of movement 66 aroundthe axis of the shaft 46 during rotation thereof.

Formed integral with the supporting section 60 is a casing 66 having areed switch 67 mounted therein with a hermetical seal. The switch 67 ispositioned close to the flat wall of the section 60 in close proximityto the interior surface of the chamber 65. The switching elements 65 ofthe switch 67 have their actuating ends positioned in the circular pathof movement of the magnet 65 so that for each revolution of the magnetabout the axis of the shaft 46, the switch 67 will be actuatedfrom oneof its controlling conditions to the other. It will be noted that thelongitudinal axes of the switch elements 65 are positioned along a chordof the circular path of movement 66 of the actuating magnet 65. Thisprovides an acute angular relationship of these longitudinaI axes andthe path of movement 66 thereby as distinguished from a perpendicularrelationship if the elements 68 were mounted radially. By having thisacute angular relationship, more of the reed switch elements are underthe influence of the magnet 65, and there may be a greater extreme ofmisalignment of the parts or tolerances before adversely affectingprecise operation of switching mechanisms.

In order to provide an adjusting means for the switch 67 relative to theangular orientation of the registration fingers 45 so as to insureproper resetting of the machine control pulse count, the casing 59 maybe bodily moved, within narrow limits. Such movement may be necessary inorder to arrange the switch elements 68 for actuation at a preciselocation relative to the magnet 65 the position of which, in turn, isindicative of the angular orientation of the fingers 45. The adjustingmeans comprises a fixed block 69 mounted on the machine frame F adjacentthe casing section 54, and a follower 70 movably retained within theblock 69. The follower 70 projects toward the section 60 and is receivedwithin a depression 70 formed in this section. Upon vertical movement ofthe follower 70, as viewed in FIG. 6, in either direction, the casing 59will be accordingly rotated slightly, as viewed in FIG. 5. In order toimpart vertical movement to the follower 70, the block 69 is providedwith an adjusting screw 72 for forcing the follower in a downwarddirection, and an I adjusting screw 73 for forcing the followerupwardly.

For insuring precise positioning of the casing 59 and consequently, theswitch 67, an indicating means, in

the .form of a pointer 74 secured to the machine frame and indicia 74ascribed on the section 60, is provided.

FIGS. 7, 8 and -9 illustrate the cooperative operation of theregistration fingers 45, the leading edge of each sheet of paper beingregistered and fedto the printing machine, and the pinch rollers 50, 51.In FIG. 7, the sheet ','being supplied by either of the sheet supplies20 or 21 arrives just as the fingers 45 move from its dotted positiontoward the full line position during rotation of. the fingers by theshaft 46. Actually, the sheet may lag slightly in arriving at itsillustrated position. At this time, the fingers are moving, in thedirection of the arrow, at a speed slightly less than that of theleading edge of the sheet-Rotation of the fingers 45 is accomplished bythe'constant speed drive motor 30 by way of the drive belt 48 and thevariable speed device 47. The

device 47, as will be described hereinafter, is adapted to impart to thefingers, rotative speeds which are relatively fast during most of arevolution and slower during other portions of a revolution, and at anincreasing speed during sheet registration. During this portion of arevolution, when a sheet is registered on the fly," the sheet will befed to the registration station at a higher speed than when it is fed tothe processing station by the pinch rollers 50, 51. I

In FIG. 8, the sheet is shown against or going against the fingers andis registered thereby so that the leading edge is free of any skewbefore entering the processing stations of the machine. The rotativespeed of the fingers continues to increase until they reach the fullline positionshown in FIG; 9. At this instant the fingers are moving ata speed equal to the machine processing speed so that the sheet will bepicked-up by the pinch rollers 50, 51 for further movement through themachine. After the leading edge of the sheet has been picked up by thepinch rollers, which are running at process speed, the fingersexperience a relative fast speed, attaining its maximum speed at aboutthe position shown in dotted lines in FIG. 9. In leaving the leadingedge of the sheet in FIG. 9, the fingers 45 must arrive at the positionshown in dotted lines in FIG. 7, which is indicative of its slowestspeed during a complete revolution, in time to catch the next followingsheet. If there is to be precise sheet feed through the processingstations of the machine, each sheet must be precisely spaced one fromanother as occurs as a result of the registration mechanism hereindescribed. Assuming that the spacing between sheets for very high speedmachine operation is to be approximately one and one-half inches, itwill be apparent that the fingers must move very swiftly through thatportion of their revolution when returning from the position shown inFIG. 9 to the position shown in FIG. 7 in order to assure this spacing.

For typical speed relationships for sheet feeding, registration andmachine processing, the mechanism so far described is adapted asfollows: Assuming the machine processing speed is 20 inches per second;that is, each sheet must be introduced to the transfer nip C at thisspeed and all other processing stations are functioning approximately atthis speed, it is desirable that the sheet supply speed be greater inorder to insure time for proper registration and to speed up totalmachine operation. Greater sheet supply speed also minimizes the effectof inefficiencies or mis-timing in the sheet supplying devices 20, 21.Preferably, the sheet supply feed is approximately 30 inches per second.Under these circumstances, the fingers 45 must slow each sheet from aspeed of 30 inches per second to a speed of 20 inches per second inmoving through the positions shown in FIGS. 7, 8 and 9. In accomplishingthese actions, the fingers as shown in full lines in FIG. 9 are at aneffective speed such that the sheet travels at 20 inches per second atthe instant when sheet registration occurs, and the reset switch 67 hasbeen actuated. Actually, the speed of the fingers increases slightly inmoving from the positions of FIG. 7 to FIG. 9, attaining the processspeed at sheet registration. After this occurs, faster increases infinger rotative speed are imparted to the fingers so that at theirdotted line positions in FIG. 9, their speed may-approximate 40 inchesper second, the maximum so attained. After this, the speed may graduallylessen until the dotted position of FIG. 7 is reached wherein the speedmay be approximately 18 inches per second, a speed lower than processspeed and the minimum for any one complete rotation of the fingers.After leaving the dotted position of FIG. 7, the fingers will be inposition to intercept the leading edge of a sheet.

With the sheets being moved to the registration zone, defined by thedotted position of the fingers in FIG. 7, to the full line position ofFIG, 9, at a greater speed than process speed, it will be apparent thatafter the fingers have moved from the dotted line position of F IG. 7,ahead of an oncoming sheet, they will be eventually contacted by thesheets leading edge as they move from the FIG. 7 position to the FIG. 9position. This contact may occur any time during this travel, dependingupon the efficiency of the sheet supplies and their respective conveyingmeans. It will be appreciated that this arrangement permits the preciseregistration of each sheet and the precise positioning thereof in themachine processing system for a fairly wide range of inaccurately timedsheet feeding to the registration zone. The defined registration zonethen is a registration window having a width in which registration cantake place. This window corresponds to approximately 90 of rotation ofthe fingers and allows a relatively wide margin of error in positioningof sheets of paper by the individual sheet supplies. During this travelof a sheet through the registration zone, it is only necessary that itbe in contact with the fingers at the time registration is to beeffected.

During movement of each sheet through the registration zone, regardlessof when the leading edge contacts the fingers, the speed of the sheetwill be slower from its entry speed of 30 inches per second to somethingless than the process speed of inches per second and then stabilized atthe process speed at registration. While at the slower speeds, thesheets will continue to experience a feeding force produced by either ofthe transport conveyors 40 or 42. During this time, the, belts of thetransport will slip relative to the adjacent surfaces of the sheets. I

In the above description of the speed relationships,

various speeds were recited in order to emphasize or illustrate therelationships. The speeds so assigned to this description are onlyillustrative and need bear no resemblance in fact. What is important arethe relationships of the speeds of the moving elements in thedescriptions. As previously stated, the registration fingers 45 rotatewith their shaft 46 at variable speeds, and this motion is imparted byway of .the variable speed device 47. This device includes an innercylindrical element 75 which is in the form of a pulley to which thebelt 56 is applied for effecting rotation of the pinch rollers 50, 51.Mounted on and exteriorly of the element and concentric therewith, is acircular member 76 which is also in the form of a pulley. The drive belt46 is applied to this member for imparting, eventually, rotation to theregistration fingers 45. The pulley member 76 is rotatably related toand held upon the cylindrical element 75 by a retaining ring 77 on oneside and by a flange 76, formed on the element, at the other end. Aflexible ring-type clutch element 60 retained between cooperatingsurfaces of the element 75 and member 76 serves as a clutch therefor.Rotation of the pulley member 76 in one direction will impart rotationto the pulley element'75 in the same direction, but rotation of thepulley member 76 in the reverse direction will have no effect upon thepulley element 75.

The element 75 and therefore the member 76 and clutch element 80 aresupported upon a cylindrical retaining block 81 which is formed atoneend with a flange 82 arranged to be secured against movement to themachine frame. Surrounding the peripheral surface of the cylindricalblock is a circular needle bearing 63 held in place by the flange 82 anda detachable circular plate 84. The inner surface of the element 60 isforce fitted to the bearing 83 and in this way the structure 75, 76 and80 is mounted for rotation upon the fixed block 81.

The block 81 is formed with a through opening as having its axiseccentric relative to the axis of the. block. The registration shaft 46projects through this opening and has its axis also eccentric relativeto the block 81. At the end of the shaft 46 which terminates within thecylindrical member 76 there is detachably secured an actuator arm 66 soas to be rotatable therewith. The arm 66 is formed with a slot 87 havingits longitudinal axis normal to the axis of the shaft46 so as to be ableto define a path'of revolution. A drive pin 88, formed on the innercylindrical surface of the element extends into the slot 67 and isadapted to travel reciprocably therealong. The parts so far describedare arranged so that the pulley element 75 and the pulley member 76 havetheir axes of rotation, designated by the numeral 96, coincident withthe axis of the block 61 and eccentric relative to the axis of the shaft46. During driving rotation of the pulley member 76, the pulley element75 is driven therewith thereby causing revolving of the drive pin 66about the axis 90. As the drive pin revolves, it imparts rotation ,tothe arm 86 which in turn, imparts rotation to the shaft 46. Continuousrevolving action by the pin 66 at constant speed, and its cooperatingreciprocating movement relative to the slot 67, will impart variablespeeds of rotation to the registration fingers 45. i

In FIGS. 7, 6 and 9, the drive pin 88, the actuating arm 66, the slot67, the axis 90, and the shaft 46 are shown in their relative positionsfor imposing the variable rotative motion upon the registration fingers.In-

FIG. 7, the revolving path of movement 160 for the pin 66 is shown asconcentric to the axis 90 and eccentric relative to the axis of theshaft 46. In the dotted position of the arm 66, the rotative speedthereof is slowest and the pin 66 is on one side of the axis 90 ordiametrically opposed relative to the axis of the shaft 46. As the pinmoves downwardly from this position, the rotational speed of the fingersincreases since the pin is moved out of its diametrically opposedrelationship and toward a position which is on the same side of the axis96 as the shaft. In FIG. 6, this repositioning is shown in progress andin FIG. 9, completed. The dotted position of the arm 66 in FIG. 9 isindicative of the highest rotative velocity attained by the registrationfingers since the pin 66 and the axis of the shaft 46 are along the sameradial line from the axis 96. In approaching this alignment, therotative speed of the fingers continue-to increase as the positioning ofthe arm 86 in full line attests. I

While the rotational velocity of the fingers 45 varies, as describedabove, the effect of the variation upon a sheet of paper beingregistered will be modified somewhat. In moving through the registrationwindow, tha is, from FIG. 7 to FIG. 9, the effective radius of thefingers 45 relative to the leading edge of a sheet S will also vary.This variation is slight, however, and for that range, its effect willbalance out. In moving from the position of FIG. 6 to that of FIG. 9,the critical portion of the window, the rotative velocity of the fingersincreases slightly. This slight increase however is factored into thespeed relationship of the fingers as they rotate and does not of itselfaffect sheet speeds.

In order to extend the effectiveness of the window width,-that is,provide more 'width-to-paper-travel, or conversely, lesspaper-travel-to-width ratio, the fingers are formed with curved surfaces101 which extend back toward the sheet supplies, to be contacted atdifferent points thereon by each sheet being registered as they travelthrough the window. For the illustrated configuration, and for the fullwindow width, distance of movement of the sheet is 10 percent less thanthe movement of the fingers. Thus, registration and accurate sheetpositioning relative to pitch reset can be accomplished in a shorteneddistance of paper travel than what would normally be required toaccomplish these functions. Or, to put it another way, a longer sheettravel is available for insuring these functions than what wouldnormally be effected if the curved surface 101 were not utilized on thefingers. The surfaces 101 are also arranged so that the leading edge ofeach sheet will orient as near as possible perpendicular to the surfaceand not slide off the surface during travel through the registrationzone. At the instant a sheet is registered and at the nip of the rollers50, 51, the surfaces 101 are exactly normal to the plane of the sheet.

The reset switch 67 is in circuit with the pulse counter 37 which may bepart of the machine logic LE, and actuation of the switch will initiatepulse recounting until subsequent actuation, in turn, producecorresponding re-counting. In this manner, pitch reset is accomplishedoff the registration mechanism and is utilized as the starting point, atleast countwise, for machine control, processing and sheet monitoring.

The logic equipment LE is operatively connected to the pulse generator36, the counting mechanism 37, clutches (not shown) for the paper sheetsupplies 20,21, the illumination lamps L to the corotrons 13, 27, themotor for the brush 28, the fuser 24 and the developing apparatus 17,and arranged so that these devices are functionally activated andcontrolled by a different counted number of the pulses in time sequence.Since the photoreceptor belt 12 is continuously being exposed byflashing imaging rays, the belt may contain a number of electrostaticimages, for example, five or more images between the exposure andtransfer stations. Similarly, the paper path between the paper suppliesand the transfer station C may contain two or three sheets. Anyparticular time cycle made operative by the timing arrangement may thenproduce sequential operation of the above-mentioned devices in an orderwhich affects different images, transfer operations and sheets of paper.In other words, the programming control system will maintain timingcontrol for five or more pitches concurrently processwise. For instance,after the machine has been turned On and the drive means 30 is in fulldrive operation so that control pulses are being produced, counted andreset by the reset switch 67, and the registration fingers are rotating,poised for the expectant sheets, the lamps L may be energized as thefirst event when the machine is placedin print condition. It will benoted that upon initial machine use, a sheet S will not have beenseparated from one of its supply stacks before the first flash of anoriginal D is made. In fact, there may be experienced two or three imageexposures on the belt 12 before the first sheet is separated from astack by one of the control pulses in the control signal. The first of aseries of produced latent images may be in or nearing the developingzone, and as images are so produced, the first one, now developed, isadjacent the transfer station in timed relationship to a sheet beingregistered. The short distance yet to travel after the registrationfingers 45 leave the sheet is factored into the pitch distance belt 12travels so that the developed image and the exact positioning it is tooccupy on the sheet will be in precise registration at transfer. Duringthe actuation of these process devices, other devcies may be activatedto continue the processing of reproductions. For example, all thecorotrons would have been energized as well as the paper jam detectiondevices (not shown) located along the paper path of movement may besensed in sequence for the different sheets of paper in the path inorder to insure the proper positioning of the sheets. The fuserapparatus would have been energized before the first sheet arrived thereand successive energization of the cleaning and discharging elementsalso would have occurred. Upon release of the sheet of paper from thenip at station C, the cycle begins again and will produce the identicalseries of operations as discussed above.

While the invention has been described with reference to the structuredisclosed, it is not confined to the details set forth but is intendedto cover such modifications or changes as may come within the scope ofthe following claims.

We claim:

I. In an electrostatic printing apparatus for reproducing copies of anoriginal having an endless movable photoreceptor surface and a pluralityof processing stations arranged when activated for producingelectrostatic latent images on the surface, for developing the images,for feeding sheets of support material, and for transferring developedimages to moving support material, and programming circuit meansoperable in cycles of control signals for controlling processing of eachcopy reproduced by the printing apparatus at one copy for each cycle,the improvement comprising:

a movable abutment engageable with the sheets of support material toregister each sheet as the same moves toward the transfer processingstation whereat developed images are transferred, means for moving saidabutment into and out of engagement with the sheets, and

switching means connected in the programming circuit means fordetermining the cycles of the programming circuit means and actuableinto a controlling condition for each registered sheet of supportmaterial, said switching means including a switch, and an actuatorelement operatively connected to the movable abutment for actuating saidswitch for each sheet of material moving past a predetermined positionin its movement toward the transfer station.

2. The apparatus of claim 1 including a shaft rotatably supporting saidabutment and wherein said actuator is mounted on said shaft to berotated with said abutment.

3. The apparatus of claim 1 wherein said switch is adjustably supportedrelative to said predetermined position.

4. The apparatus of claim 1 wherein said switch includes switch elementsmovable into and out of contact and said actuator element includes amagnet arranged for movement adjacent said elements for controllingcontacting thereof.

5. In an electrostatic printing apparatus for reproducing copies of anoriginal on sheets of support material and including processing stationsselectively actuable to electrostatically produce and develop images onthe support sheets,

control means for controlling actuation of said processing stations toproduce copies, and

means for generating control signals during operation of said apparatus,the improvement comprising:

means for locating and registering said support sheets, said locatingmeans including a switch adapted when in a preselected position toidentify a predetermined block of said control signals; and signalresponsive means for operating said control means through apredetermined program cycle in which said processing stations areactuated in accordance with certain ones of said control signals fromsaid block of signals to produce copies.

1. In an electrostatic printing apparatus for reproducing copies of anoriginal having an endless movable photoreceptor surface and a pluralityof processing stations arranged when activated for producingelectrostatic latent images on the surface, for developing the images,for feeding sheets of support material, and for transferring developedimages to moving support material, and programming circuit meansoperable in cycles of control signals for controlling processing of eachcopy reproduced by the printing apparatus at one copy for each cycle,the improvement comprising: a movable abutment engageable with thesheets of support material to register each sheet as the same movestoward the transfer processing station whereat developed images aretransferred, means for moving said abutment into and out of engagementwith the sheets, and switching means connected in the programmingcircuit means for determining the cycles of the programming circuitmeans and actuable into a controlling condition for each registeredsheet of support material, said switching means including a switch, andan actuator element operatively connected to the movable abutment foractuating said switch for each sheet of material moving past apredetermined position in its movement toward the transfer station. 2.The apparatus of claim 1 including a shaft rotatably supporting saidabutment and wherein said actuator is mounted on said shaft to berotated with said abutment.
 3. The apparatus of claim 1 wherein saidswitch is adjustably supported relative to said predetermined position.4. The apparatus of claim 1 wherein said switch includes switch elementsmovable into and out of contact and said actuator element includes amagnet arranged for movement adjacent said elements for controllingcontacting thereof.
 5. In an electrostatic printing apparatus forreproducing copies of an original on sheets of support material andincluding processing stations selectively actuable to electrostaticallyproduce and develop images on the support sheets, control means forcontrolling actuation of said processing stations to produce copies, andmeans for generating control signals during operation of said apparatus,the improvement comprising: means for locating and registering saidsupport sheets, said locating means including a switch adapted when in apreselected position to identify a predetermined block of said controlsignals; and signal responsive means for operating said control meansthrough a predetermined program cycle in which said processing stationsare actuated in accordance with certain ones of said control signalsfrom said block of signals to produce copies.